Take an awe-inspiring tour of New London, the Navy's most important submarine base

Naval Submarine Base New London is one of the US Navy's most important and fascinating facilities.

Located along the eastern bank of the Thames River in Groton, Connecticut, New London is home to 15 attack-class submarines, the largest single contingent of subs in the US Navy. The submarines serve throughout the world, including beneath the polar ice cap.

Almost every sailor serving aboard a submarine will pass through New London for some kind of training. The base is known as "home of the submarine force."

And personnel at the base like to call New London the "submarine capital of the world."

Steeped in history, in 1915 Submarine Base New London the first port to host US submarines, not long before the country's entrance into World War I. Since then, the base has continuously expanded as the US has grown into the world's largest naval power with the most advanced submarine fleet on earth.

In October of 2014, Business Insider was given an all-encompassing tour of the base and its operations.

Naval Submarine Base New London started as a Naval Yard and Storage Depot in 1868 but didn't host submarines until 1915, two years before the US entered World War I.

New London has continuously grown. In the 1960s, the base had expanded beyond the waterfront and into the surrounding hills.

Today the base is the home port of 15 attack subs. Its 10 piers allow it to berth 18 of the vessels. And the base has plans to expand even more over the next two decades.